A Levels Biology (9700)•9700/12/M/J/23
Explanation
The Universal Genetic Code in DNA
Steps:
- Define the universal genetic code as the shared system where DNA triplets (codons) specify the same amino acids across organisms.
- Recall that this code uses 64 codons for 20 amino acids and stop signals, nearly identical in all life forms.
- Evaluate choices: A matches the shared triplet system; B misstates codon uniqueness; C is grammatically incorrect and false; D confuses bases with the code.
- Confirm A as the precise definition of universality.
Why A is correct:
- The universal genetic code means all organisms translate the same codon sequences into identical amino acids, per the standard genetic code table.
Why the others are wrong:
- B: Most codons code for the same amino acid (redundancy), not different ones.
- C: Incorrect phrasing and false; many codons share amino acid assignments.
- D: While true for bases (A, T, C, G), it doesn't define the code's triplet-amino acid mapping.
Final answer: A
Topic: Protein synthesis
Practice more A Levels Biology (9700) questions on mMCQ.me